382 



Memoir Sears Foundation for Marine Research 



Snout in front of eyes about 75—80 "/o as long as distance between outer margins 

 of orbits on young, increasing to about 85 "/q on adults; its length in front of mouth 

 about 1.8— 2.1 times as great as distance between exposed nostrils and about 85—90 % 

 as great as distance between first gill openings in young, 65—70 "/(, as great in adults. 

 Eyes about 65—70 "/o as long as distance between them and about 75— go^/o ^s long 

 as spiracle. Distance between inner ends of first gill openings about 2.2—2.6 times as 

 long as distance between exposed nostrils; distance between inner ends of fifth gills 

 about ^8 as long as distance between inner ends of first gills. Posterior margin of nasal 



Figure 92. Dasyatis say. Midbelt of back from eye to origin of tail spine of adult male, 615 mm wide, from 

 Rio de Janeiro (Harv. Mus. Comp. Zool., No. 989), showing mid-dorsal and scapular tubercles as well as 

 claspers. 



curtain nearly straight, its free edge finely fringed, the individual marginal lobelets 

 simple or bifid. Upper jaw moderately arched forward in females, more strongly so in 

 mature males but projecting a little rearward centrally; lower jaw weakly recessed in 

 midline to correspond. Floor of mouth with a transverse series of three stout papillae 

 centrally; another smaller papilla on either side. 



Teeth^^* ls^6> uppers largest about midway between center of jaw and outer cor- 

 ners; lower teeth about equally large in all series, except somewhat smaller near outer 

 ends of tooth band; teeth of females and immature males quadrangular with blunted 

 corners, about as broad (transversely) as long (anteroposteriorly), the functional surface 

 weakly rounded or more or less irregular from wear; those of mature males with low 

 and broadly triangular cusp, largest in the youngest rows. About 6—7 rows in function 

 on upper jaw; 10-12 rows exposed centrally on lower jaw, 6-7 rows near outer corners. 



Pelvics reaching rearward only a little, if at all, beyond rear limits of pectorals, 



128. Counted along widest part of tooth band. 



